The present invention relates to an improved tent frame and particularly a tent frame that is capable of folding conveniently and has a center pole located in the center for lifting the tent.
Conventional tent frames generally include a plurality of upright poles each coupled with a grommet. Two neighboring poles are pivotally engaged with two sets of a first and a second brace pole which are crossed with each other and are pivotally engaged on a pivotal shaft. The adjacent first and second brace pole between two upright poles engage respectively with a pivotal element. The first brace pole has two parallel connecting plates located in the center and, two separating sections extended in opposite directions which have respectively one end pivotally engaged with the connecting plate. One separating section has one end remote from the connecting plate and pivotally engaged with the pivotal element. Another separating section has one end remote from the connecting plate and pivotally engaged with the grommet. Two connecting plates form a passing groove allowing the second brace pole to run through. The second brace pole in the passing groove and the two connecting plates are pivotally engaged with the pivotal shaft. After assembly of aforesaid elements, the two separating sections pivotally engaged with the pivotal element may be set on a same surface.
Whereas adopting the construction set forth above, the tent is lifted only at supporting spots formed by supporting poles at four ends. The center portion of the tent does not have any support and tends to sag. To prevent this from happening, users must fasten the four ends of the tent and supporting poles tightly, or stretch the tent forcefully. It takes a lot of human labor to accomplish the task. An unevenly stretching on one side will decrease the stretching effect or even cause damage to the tent.
The primary object of the invention is to resolve the foregoing disadvantages. The invention provides a folding tent frame that has a center pole for lifting the tent. Moreover the invention has post sets located at four ends. Two neighboring post sets engage respectively with a first linkage rod set and a second linkage rod set. The first linkage rod set of one post set and the second linkage rod set of a neighboring post sets are engaged with each other through a first driven rod set and a second driven rod set which in turn are pivotally engaged with each other through toggle joints in a cross and staggered manner. The first and second driven rod sets engage with each other at a juncture which in turn engage with a passive bar set pointing toward the center. There are total four passive bar sets joining in the center to engage with the center pole. The first and second linkage rod sets, the first and second driven rod sets, and the passive bar sets are pivotally engaged with one another on toggle joints. The post sets may be moved away or towards the center pole and drive aforesaid rod sets and bar sets for extending or folding the tent frame.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.